MIAMI, FLA., 1904. 4 25 



without increased value. In the Florida samples reported the moisture 

 ranged from 51 per cent in a common Florida variety grown in the field 

 to 74 per cent in an imported sweet variety (No. 9674) grown in a nur- 

 sery. This represents a difference between these two samples in dead 

 weight equivalent to one-fourth of the tonnage. Evidently in the 

 selection of varieties an effort should be made to reduce the moisture 

 to a minimum. 



SIZE AND FORM OF TUBERS. 



In connection with the starch and moisture determinations a study 

 was made of the size and form of the tubers, the results of which are 

 shown in Table VIII. The tubers are divided into six classes accord- 

 ing to form, i. e., cylindrical, partly taper, taper, oval, club, and 

 dumb-bell shaped, and the tubers of each cluster were classified 

 accordingly as accurately as possible, though no sharp dividing line 

 can be drawn. 



The classification was made with the idea that some relation might 

 exist between the shape of the tuber and its starch and hydrocyanic- 

 acid content. Apparently, however, no such relation exists, though 

 the nursery propagation to which the Miami plants were subjected 

 may have modified their growth, the plants being through necessity 

 grown in clusters and somewhat crowded as compared with plants 

 grown in hills as in field culture. 



The form of the tuber is a factor- in plant selection second only in 

 importance to the content of hydroc3 T anic acid. It was shown in the 

 study made at Biloxi that the hydroc} T amc acid was found principally 

 in the cortical layer or peel, the relative amount of which is dependent 

 upon the form of the tuber. Further, the ease with which the roots 

 are pulled in harvesting is largely dependent upon their shape. 



From a study of these plants, and many others, it appears that the 

 most desirable forms of tubers are the cylindrical and the oval. The 

 "partly taper" roots probably are formed when a cylindrical tuber is 

 insufficiently nourished and shrinks at the end, while the taper form 

 occurs when the root was not well nourished from the beginning and 

 in consequence suffered a regular shrinkage. The dumb-bell form 

 may be caused by an oval tuber taking on a, second growth and then 

 maturing, while the club form represents a second growth that did 

 not mature. 



In making up Table VIII the tubers of the greatest diameter and 

 length were placed in column 1, which therefore represents the best 

 tubers of the series. It will be noted that No. 1 occurs as club-shaped 

 thirteen times, more than double the number of times that it appears 

 as any other form. It is possible that the natural selection has been 

 from tubers of the oval class. The latter form is better adapted to 

 harvesting and handling and contains the minimum percentage of 

 surface or cortical la}'er, which indicates an increase in starch and a 

 decrease in hydrocj'anic acid. 



